Abitualmente, per eseguire il dosaggio del quadro lipidico si consiglia il digiuno notturno di 8-12 ore.
Negli ultimi anni questa indicazione sta cambiando. Alcune linee guida hanno infatti incominciato a dare la possibilità di dosare il quadro lipidico anche in condizioni di non digiuno, dal momento che potrebbe essere maggiormente predittivo della sua aterogenicità. Noi infatti trascorriamo la maggior parte della nostra giornata in una situazione postprandiale...
BACKGROUND: Recent recommendations favoring nonfasting lipid assessment may affect low-density lipoprotein cholesterol (LDL-C) estimation. The novel method of LDL-C estimation (LDL-CN) uses a flexible approach to derive patient-specific ratios of triglycerides to very low-density lipoprotein cholesterol. This adaptability may confer an accuracy advantage in nonfasting patients over the fixed approach of the classic Friedewald method (LDL-CF).
METHODS: We used a US cross-sectional sample of 1?545 ?634 patients (959?153 fasting =10-12 hours; 586?481 nonfasting) from the second harvest of the Very Large Database of Lipids study to assess for the first time the impact of fasting status on novel LDL-C accuracy. Rapid ultracentrifugation was used to directly measure LDL-C content (LDL-CD). Accuracy was defined as the percentage of LDL-CD falling within an estimated LDL-C (LDL-CN or LDL-CF) category by clinical cut points. For low estimated LDL-C (<70 mg/dL), we evaluated accuracy by triglyceride levels. The magnitude of absolute and percent differences between LDL-CD and estimated LDL-C (LDL-CN or LDL-CF) was stratified by LDL-C and triglyceride categories.
RESULTS: In both fasting and nonfasting samples, accuracy was higher with the novel method across all clinical LDL-C categories (range, 87%-94%) compared with the Friedewald estimation (range, 71%-93%; P=0.001). With LDL-C <70 mg/dL, nonfasting LDL-CN accuracy (92%) was superior to LDL-CF accuracy (71%; P<0.001). In this LDL-C range, 19% of fasting and 30% of nonfasting patients had differences =10 mg/dL between LDL-CF and LDL-CD, whereas only 2% and 3% of patients, respectively, had similar differences with novel estimation. Accuracy of LDL-C <70 mg/dL further decreased as triglycerides increased, particularly for Friedewald estimation (range, 37%-96%) versus the novel method (range, 82%-94%). With triglycerides of 200 to 399 mg/dL in nonfasting patients, LDL-CN <70 mg/dL accuracy (82%) was superior to LDL-CF (37%; P<0.001). In this triglyceride range, 73% of fasting and 81% of nonfasting patients had =10 mg/dL differences between LDL-CF and LDL-CD compared with 25% and 20% of patients, respectively, with LDL-CN.
CONCLUSIONS: Novel adaptable LDL-C estimation performs better in nonfasting samples than the fixed Friedewald estimation, with a particular accuracy advantage in settings of low LDL-C and high triglycerides. In addition to stimulating further study, these results may have immediate relevance for guideline committees, laboratory leadership, clinicians, and patients.